A rechargeable hybrid vehicle comprises a conventional combustion drivetrain (with an internal combustion engine and a fuel tank) and an electric drivetrain (with an electric motor and a traction battery notably capable of charging at a power outlet).
Such a hybrid vehicle is capable of being drawn along just by its electric drivetrain alone, or by its combustion drivetrain alone, or even simultaneously by its two electric and combustion drivetrains. It is also possible to recharge the traction battery by taking advantage of the power developed by the internal combustion engine, or also by recovering the kinetic energy developed by the motor vehicle on braking.
Due to ignorance of the vehicle's future journey, the strategy currently implemented for using one or other of the drivetrains consists in systematically beginning by discharging the traction battery at the start of the journey until reaching a level of minimum energy, then using the combustion drivetrain. In this way, when the driver makes short journeys and has regular opportunities to recharge the traction battery, they use the electric drivetrain to the maximum, which reduces the pollutant emissions of the vehicle.
This strategy does not, however, always ensure minimum fuel consumption. This is notably the case when the user begins a journey via a freeway part and ends it with a part in town. Indeed, the use of the electric drivetrain is unsuited to the freeway since the traction battery discharges very quickly thereon, and the use of the combustion drivetrain is unsuited to town since the internal combustion engine's performance is lower in town than on the freeway.
In order to overcome this drawback, document U.S. Pat. No. 8,825,243 discloses how to construct an “ideal” discharge curve of the battery on a journey prediction known to a navigation system, this curve being constructed so that the charge state of the battery reaches its minimum permissible value only at the end of the journey, then how to control the hybrid system on this journey prediction so as to best follow this discharge curve. The drawback of such a solution is that in case of significant diversity of highway conditions on the journey, e.g. the simple but very common case when starting on a first section in town, then continuing on a second freeway section and finally ending on a third section in town, then the journey is performed in a non-optimal manner from the point of view of energy consumption.
The use of the combustion drivetrain in town further proves less pleasant for the driver than that of the electric drivetrain.
Finally, legislation sometimes prevents the use of the internal combustion engine in town, so that the driver then no longer has access to town.